diff --git a/.circleci/config.yml b/.circleci/config.yml
index 8cdbcd5aadaa3..f6a00b6296204 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -77,6 +77,7 @@ env-arm64: &env-arm64
 
 env-mas: &env-mas
   GN_EXTRA_ARGS: 'is_mas_build = true'
+  MAS_BUILD: 'true'
 
 # Misc build configuration options.
 env-enable-sccache: &env-enable-sccache